# Copy the backup from gcloud to local fs
/snap/bin/gsutil cp “gs://bucket/DB.xbstream” /path/local/DB.xbstream
# Extract
xbstream -xv -C /path/to/restore < /path/local/DB.xbstream
# Pepare
xtrabackup prepare --target-dir /path/to/restore
# Fix permissions
chown -R mysql:mysql /path/to/restore
# Start mysql
systemctl start mysql
Our documentation has many HOWTO examples on the above.